This invention relates to an apparatus for drying substantially ellipsoid products which are conveyed over a conveying path by means of a conveyor, the apparatus comprising a first number of nozzles which are connected to a compressor.
In some countries, it is mandatory to wash eggs before they are packed. Moreover, some packers believe that the impression of hygiene and quality is enhanced when eggs, before being packed, are washed, so that manure and feathers are removed from the eggs. After washing the eggs, it is important that the eggs be dried as soon as possible. In fact, when drying is deferred too long, the moisture with which the eggs have been washed migrates through the porous shell and thus affects the taste and/or the quality of the egg. It may also be advantageous to wash ellipsoid products other than eggs, for instance fruit.
For drying eggs, various apparatuses are known, which apparatuses are described in, for instance, U.S. Pat. No. 4,173,831, U.S. Pat. No. 4,750,277 and JP-U-3-2134.
In these known apparatuses, the dry air is blown down from above, perpendicularly to the plane of conveyance. A drawback of the known apparatuses is that after the ellipsoid products have passed a first number of nozzles in a first drying section, moisture still remains on the conveyor. Because of the fact that the conveyors are mostly roller conveyors, and the ellipsoid products are rotated over at least some parts of the conveyor path, the moisture on the conveyor rollers is spread again over the substantially dried ellipsoid products. As a consequence the drying result is not satisfactionary. A further drawback of the known apparatuses is that in order to achieve an acceptable drying result, a huge amount of air needs to be blown onto the eggs Upon visual inspection of the eggs dried with the known apparatuses, a dried surface percentage of about 70% is observed. A flow rate of 1500 m3 per 10,000 eggs per hour, with the pressure being about 50 mbar (5,000 Pa) at the outflow slots, is not unusual in the known apparatuses. In a machine in which twelve rows of eggs are conveyed side by side, with a capacity of 10,000 eggs per row per hour, this requires a power of 54 kW. According to standardized measurements, the noise level produced as a result of the large amount of air being blown out is certainly 95-105 dB (A), which makes it necessary to encase the entire drier. Such a large amount of drying air which is blown down vertically above the eggs with a fairly low pressure leads to the drying result of about 70%, which in itself is little satisfactory. In particular at the points of an egg, that is, at the opposite ends with the highest degree of curvature, there is a substantial chance that moisture will remain present there after the egg has passed the drier.
The object of the invention is to adapt the apparatus of the type described in the opening paragraph hereof , such that it no longer has the above-described disadvantages. To that end, the invention provides an apparatus for drying substantially ellipsoid products which are conveyed over a conveying path by means of a conveyor, the apparatus comprising a first number of nozzles which are connected to a compressor forming a first drying section, wherein at least one rotating brush is arranged under the conveyor such that the at least one brush contacts an underside of the conveyor for removing water therefrom.
Water which has been blown off from the ellipsoidal products and which is still remaining on the conveyor will be removed by the at least one brush which is rotating under the conveyor such that it wipes off water from the conveyor. Especially, when the conveyor is a roller conveyor of which the rolls rotate at least over a certain part of the conveyor path the presence of the brush is of the utmost importance in order to avoid that water which has been blown off again is spread over the ellipsoidal products. A roller conveyor is particularly favorable because the products can be rotated as they pass the nozzles, which yields a greater product surface exposed to direct blowing action.
According to a further elaboration of the invention, a wipe bar arranged parallel to the brush may be present such that brush hairs of the brush wipe against the wipe bar for wiping off the water from the brush.
The apparatus may be provided with two drying sections for achieving a better drying result. To further improve the drying result suction openings may be provided under the conveyor, which suction openings are connected to a suction pump for creating a reduced pressure under the conveyor. Water drips hanging at the under side of the ellipsoid products can be removed by these suction openings.
According to a further elaboration of the invention, the nozzles may be designed and arranged relative to the conveying path such that the drying air blown out by these nozzles has a main flow direction which is both directed substantially perpendicularly to the surface of a passing product and blows directly onto at least the areas adjacent the points of a passing ellipsoid product. As a result of the fact that the nozzles blow the drying air substantially perpendicularly to at least those surface portions of a passing product that are located adjacent the points of the passing product, at the points of the product which are difficult to dry, still an excellent drying result is obtained. The term xe2x80x98pointsxe2x80x99is herein understood to refer to those portions of the ellipsoid product where the curvature of the surface is strongest, i.e., essentially the positions where the longitudinal axis of the ellipsoid product intersects the surface of the product. Substantially halfway the two points on the: longitudinal axis lies the center of the egg. The nozzles are designed and arranged such that the drying air blown out by them is directed substantially at the middle of a passing product and also blows directly upon the areas adjacent the points of the product. In that way, upon visual inspection, a dried surface percentage of at least about 90% is observed.
According to a further elaboration of the invention, the surface exposed to direct blowing can be further enlarged when the rollers, for the purpose of their rotation, are driven such that the movement of the upwardly facing side of the products, which movement occurs as a result of the rotation, has a direction which is equal to the conveying direction of the conveyor.
It is then preferred when, according to a further elaboration of the invention, the rotational speed of the rollers and the distance of the nozzles are adjusted to each other such that each product, after passing the nozzles, does not have any shell surface portion, at least adjacent the points of the product, that has not been directly blown upon by drying air from one of the nozzles.